<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <!-- 开发环境版本，包含了有帮助的命令行警告 -->
  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
</head>

<body>
  <style>
    ul li {
      float: left;
      margin-left: 20px;
      list-style: none;
      display: inline-block;
      margin-top: 10px;
      cursor: pointer;
    }



    .active {
      color: pink;
      border-bottom: 5px solid pink;

    }
  </style>
  <div class="root">
    <ul v-for="(k,i) in list" :key="i">
      <li :class="{'active':index === i}" @mouseover="show(i)">{{k}}</li>
    </ul>
  </div>
  <script>
    //创建vue实例
    new Vue({
      el: '.root', //指定当前vue 为哪个容器使用
      data: {
        list: ['热门', '咖啡', '饮食', '男装', '女装', '眼睛', '内衣', '内裤'],
        index: 0
      },
      methods: {
        show(i) {
          this.index = i
        }
      }
    });

  </script>
</body>

</html>